How is CVE-2016-6787 a UAF bug in Linux kernel?
Clash Royale CLAN TAG#URR8PPP
From the explanation video of the Linux kernel vulnerability CVE-2016-6787, I don't understand is though put_ctx isn't inside a mutex, there's an atomic_dec_and_test inside put_ctx at the very beginning. kfree_rcu is only invoked if atomic_dec_and_test returns 1. How come two threads become racy then? Where is ctx getting used after the free operation?
vulnerability
asked Dec 24 '18 at 2:53
Holmes.Sherlock
29435
migrated from unix.stackexchange.com Dec 25 '18 at 4:52
This question came from our site for users of Linux, FreeBSD and other Un*x-like operating systems.
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From the explanation video of the Linux kernel vulnerability CVE-2016-6787, I don't understand is though put_ctx isn't inside a mutex, there's an atomic_dec_and_test inside put_ctx at the very beginning. kfree_rcu is only invoked if atomic_dec_and_test returns 1. How come two threads become racy then? Where is ctx getting used after the free operation?
vulnerability
asked Dec 24 '18 at 2:53
Holmes.Sherlock
29435
migrated from unix.stackexchange.com Dec 25 '18 at 4:52
This question came from our site for users of Linux, FreeBSD and other Un*x-like operating systems.
add a comment |
From the explanation video of the Linux kernel vulnerability CVE-2016-6787, I don't understand is though put_ctx isn't inside a mutex, there's an atomic_dec_and_test inside put_ctx at the very beginning. kfree_rcu is only invoked if atomic_dec_and_test returns 1. How come two threads become racy then? Where is ctx getting used after the free operation?
vulnerability
asked Dec 24 '18 at 2:53
Holmes.Sherlock
29435
From the explanation video of the Linux kernel vulnerability CVE-2016-6787, I don't understand is though put_ctx isn't inside a mutex, there's an atomic_dec_and_test inside put_ctx at the very beginning. kfree_rcu is only invoked if atomic_dec_and_test returns 1. How come two threads become racy then? Where is ctx getting used after the free operation?
vulnerability
vulnerability
asked Dec 24 '18 at 2:53
Holmes.Sherlock
29435
asked Dec 24 '18 at 2:53
Holmes.Sherlock
29435
asked Dec 24 '18 at 2:53
Holmes.Sherlock
29435
asked Dec 24 '18 at 2:53
Holmes.Sherlock
29435
asked Dec 24 '18 at 2:53
Holmes.Sherlock
29435
29435
migrated from unix.stackexchange.com Dec 25 '18 at 4:52
This question came from our site for users of Linux, FreeBSD and other Un*x-like operating systems.
migrated from unix.stackexchange.com Dec 25 '18 at 4:52
This question came from our site for users of Linux, FreeBSD and other Un*x-like operating systems.
add a comment |
add a comment |
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